The present invention relates generally to stereoscopic video cameras and more particularly to a stereoscopic video camera, system, and method which uses only a single objective lens.
Cameras which can produce images having left and fight perspectives which, when viewed concurrently or sequentially, provide depth perception or a "3-D" representation of the object, are conventionally referred to as "stereoscopic" cameras. There are two general types of stereoscopic video camera systems used in the prior art. One type uses dual (left and fight) objective lenses, the images from which are directed to and focused on two separate video detectors. The outputs of each of these detectors are then processed and alternately displayed on a video monitor. However, to create the desired three dimensional stereoscopic video effect, the video monitor must be viewed with special glasses. These special glasses have left and right lenses which are alternately switched between light transmissive and opaque states, in synchronization with the alternating switched images displayed on the monitor. Thus, the viewer sees left and right hand perspective views of the object, resulting in a composite image on the screen capable of providing depth perceptive information to the viewer using the special glasses. The full image is seen concurrently because of the persistence of the monitor and of the viewer's eyes.
The second type of prior art stereoscopic video camera is a variation of the dual lens/detector system described above. In this second system, the images from each of the lenses are superimposed on a single detector. However, the images are separated in time by dual shutters that alternate between the images produced by the left and right lenses. Consequently, the output of the single detector alternates between the two perspectives given by the left and right lenses. Again, special glasses synchronized with the lens shutters are necessary to view the image on the monitor in such a way that depth perception is obtained.
There is also known in the prior art a method of forming still stereoscopic images using a single lens system. For example, in U.S. Pat. No. 4,761,066, issued to Carter, a system is described whereby still images are generated using a polarizing material to separate the two stereoscopic perspectives with a single objective lens.
Finally, U.S. Pat. No. 5,222,247 teaches the use of shuttered pupils or apertures within the optical path of an endoscopic camera lens system. However, the '247 device does not take advantage of the full circumference of the camera tube in its pupillary system nor does it offer an improved sequential color illumination and imaging method. The use of the full lens aperture adds valuable depth information and improves sensitivity.
In the case of surgical endoscopes and the like, where a need for a reduction in complexity and volume occupied by the lens system of a video camera is present, it would be preferable to have a stereoscopic video camera which can generate the image using a single lens. Such a device is lacking in the prior art.